The origins of the vertical sliding sash window are still subject to speculation and debate, but it would appear that the design probably derived from the much simpler horizontal sliding sash commonly known as the 'Yorkshire Sash'. For many years it was believed that the vertical design had originated in Holland, during the later part of the Seventeenth Century. Others claimed it to be of French origin, as the word 'sash' is derived from the French word 'chassis' , meaning frame. However the French sash had not yet developed counter-balancing and the sliding sash frame was held in place by a swivel block. The earliest recorded account may be that of W.Horman who in his 1589 'Vulgaria' wrote-

"Glasen wyndowis let in the lyght.....I have many prety wyndowes shette with levys goynge up and down".

Certainly toward the end of the Seventeenth Century, sash windows were apparent in England examples include Chatsworth House (c1676 - 1680), Kensington Palace and Hampton Court Palace. Sir Christopher Wrens master joiner, Thomas Kinward, recorded possibly the earliest specification of a fully developed sash window, whilst working at Whitehall Palace. With the royal patronage and adoption by Wren, wooden sash windows soon became a fashionable status symbol across Britain and the Colonies. Many earlier casement windows were replaced and sliding sash windows were used almost exclusively in new buildings, from royal palaces to simple cottages the sash ruled supreme and remained popular until the earlier part of this century.

The sash offered many advantages, including being better suited to the wet British climate, as it can be closed down to a narrow gap, allowing for good ventilation whilst reducing the chance of rain entering. Being contained within the box, the sashes are less susceptible to distortion and rot than a hinged casement adding greatly to their life span. Aesthetically the sash is constructed from delicate sections of wood, with large areas of glass that add a certain grace, even when open they do not detract from the facade, as an open casement does.

Georgian architecture embraced sash windows wholeheartedly, improving the design from a single moving sash, with the top being fixed, to the more familiar system of two moveable sashes. Oak was the common timber used for construction, with thick glazing bars to hold the small, valuable crown glass panes, made by blowing. The 'bulls eye' formed at the centre by this manufacturing technique was commonly used at the rear of buildings. As glass manufacture improved larger panes started to appear and the ‘classic’ Georgian design consisting of six over six panes, with narrow glazing bars became the norm.

For the Victorians, box sash windows were a central focus to the character of their buildings, inside and out they lavished ornamentation and decoration on their homes. Curved horns, multi-arched heads, intricate mouldings, leaded lights and latticework started to appear in the sashes, which were often grouped into impressive bays and offset with ornate stone reveals. Graduating the size of windows from the ground upwards not only improved the perspective but also increased the amount of light to the lower rooms.

By the turn of the century the sash was the most widely used window, but since the first world war their popularity has been in decline. This decline is probably due to the labour costs involved in their manufacture when compared to the easily mass produced wooden or metal casement window.